Under Orders Settings, enable this option If you want to record full/partial refunds in QuickBooks Online.
Enabled: All refunds, either partial or full, are recorded as Refund Receipts in QuickBooks Online. For more information, see our detailed support article here
Disabled: Refund information will not be imported from Shopify into QuickBooks Online. If required, you will need to manually record Shopify refunds in QuickBooks Online.